The present invention relates to a method and an apparatus for the thermal treatment of substrates, especially semiconductor wafers, in a process chamber having at least one element in the process chamber that influences the temperature distribution.
Such an apparatus is known, for example, from DE-A-197 37 802 of the same applicant. With this apparatus, a light-permeable process chamber is provided for receiving semiconductor wafers that are to be thermally treated. Provided outside of the process chamber are banks of heating lamps in order to vary the temperature of the substrate that is disposed in the process chamber. To achieve certain process results, in particular to achieve a homogeneous temperature distribution within the substrate, there is provided in the process chamber a compensation ring, which surrounds the substrate in a plane parallel to it, as well as a light-transforming plate, which is also designated as a hotliner, that is held spaced form the substrate and extends parallel thereto. The objective of the compensation ring is to prevent edge effects that occur during the thermal treatment of the wafer. Thus, for example, there is prevented a more rapid heating-up at the rim relative to the inner portion of the wafer during a heating-up phase, and a more rapid cooling off during a cooling-off phase. In this connection, it is known to construct the compensation ring from a plurality of individual segments, as is described, for example, in the not prepublished DE-A-198 21 007, which belongs to the same applicant.
The function of the hotliner is to absorb the light radiation emitted from a bank of heating lamps, as a result of which the hotliner is heated and itself emits a thermal radiation in order to heat the wafer. This indirect heating of the wafer serves to shield at least one surface of the wafer from a direct light irradiation, as a result of which in particular structures formed on the wafer are protected. The function of such a hotliner can be ascertained, for example, from DE-A-4 437 361, reference to which is made to avoid repetition.
With all of these apparatus, the elements that influence the temperature distribution, such as, for example, the compensation ring and/or the light-transforming plate, are provided such that during the thermal treatment they are held rigid and parallel to a plane of the wafer. Merely in DE-A-198 21 007 is a movement of the compensation ring described that serves to permit access to the semiconductor wafer during the removal and the insertion of the wafer.
Proceeding from the aforementioned apparatus it is an object of the present invention to provide a method and an apparatus for the thermal treatment of substrates with which an improved temperature homogeneity is achieved.